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Home > Archive > Alternative Power sources > April 2007 > Automatic transfer switch
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| Author |
Automatic transfer switch
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| jevansts 2007-04-25, 1:25 pm |
| I've set up an array of batteries with an inverter to power a few
computers. When the AC fails, I'd like for the computers to
automatically switch over to the battery power. Can anyone recommend a
good and inexpensive automatic transfer switch which can accomplish
this?
I imagine the setup will look like this
AC--------->Switch---->Computer
^
Batteries->Inverter
Thanks!
| |
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| jevansts wrote:
> I've set up an array of batteries with an inverter to power a few
> computers. When the AC fails, I'd like for the computers to
> automatically switch over to the battery power. Can anyone recommend a
> good and inexpensive automatic transfer switch which can accomplish
> this?
>
> I imagine the setup will look like this
>
>
> AC--------->Switch---->Computer
> ^
> Batteries->Inverter
>
> Thanks!
>
possibly better:
AC > battery charger > batteries > inverter > computer(s)
kind of an UPS, but with higher capacity depending on your battery amp
hours.
//lm
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| Steve Spence 2007-04-25, 1:25 pm |
| www.backwoodssolar.com has a 120 volt and a 220 volt unit, under $150
Good inverters have this function built-in.
--
Steve Spence
Director, Green-Trust
http://www.green-trust.org
"jevansts" <jevansts@yahoo.com> wrote in message
news:1177521575.343044.136210@n15g2000prd.googlegroups.com...
> I've set up an array of batteries with an inverter to power a few
> computers. When the AC fails, I'd like for the computers to
> automatically switch over to the battery power. Can anyone recommend a
> good and inexpensive automatic transfer switch which can accomplish
> this?
>
> I imagine the setup will look like this
>
>
> AC--------->Switch---->Computer
> ^
> Batteries->Inverter
>
> Thanks!
>
| |
| Solar Flaire 2007-04-25, 5:25 pm |
| UPS units run the computer off the batteries via inverter. The
batteries are then charged via an AC to DC battery charger. You just
need to add a charger to the formula now.
You do not want your computer "switched" or "transferred". The glitch
may destroy it or cause your 'puter to reboot.
"jevansts" <jevansts@yahoo.com> wrote in message
news:1177521575.343044.136210@n15g2000prd.googlegroups.com...
> I've set up an array of batteries with an inverter to power a few
> computers. When the AC fails, I'd like for the computers to
> automatically switch over to the battery power. Can anyone recommend
> a
> good and inexpensive automatic transfer switch which can accomplish
> this?
>
> I imagine the setup will look like this
>
>
> AC--------->Switch---->Computer
> ^
> Batteries->Inverter
>
> Thanks!
>
| |
| jevansts 2007-04-26, 1:25 pm |
| Excellent ideas!! So when the power goes off, the computers will run
from the batteries. If the batteries are depleted, and the power comes
back on, will the batteries have to recharge fully before the
computers can be used again?
Thanks!
On Apr 21, 7:02 pm, "Solar Flaire" <solarer...@hotmail.invalidater>
wrote:[color=darkred]
> UPS units run the computer off the batteries via inverter. The
> batteries are then charged via an AC to DC battery charger. You just
> need to add a charger to the formula now.
>
> You do not want your computer "switched" or "transferred". The glitch
> may destroy it or cause your 'puter to reboot.
>
> "jevansts" <jevan...@yahoo.com> wrote in message
>
> news:1177521575.343044.136210@n15g2000prd.googlegroups.com...
>
>
>
>
| |
| Neon John 2007-04-26, 1:25 pm |
| Yes. this is what is properly called a UPS. The gadgets you buy at
the computer store that kick in when the power fails are properly
called standby power supplies.
John
On 26 Apr 2007 08:53:17 -0700, jevansts <jevansts@yahoo.com> wrote:
>Excellent ideas!! So when the power goes off, the computers will run
>from the batteries. If the batteries are depleted, and the power comes
>back on, will the batteries have to recharge fully before the
>computers can be used again?
>
>Thanks!
>
>On Apr 21, 7:02 pm, "Solar Flaire" <solarer...@hotmail.invalidater>
>wrote:
>
---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
All great things are simple and many can be expressed in single words:
Freedom, Justice, Honor, Duty, Mercy, Hope. -Churchill
| |
| Solar Flaire 2007-04-26, 8:25 pm |
| No. As soon as the batteries are capable of carrying the computer it
will be useable again except for the limited reserve capacity until
fully charged.
"jevansts" <jevansts@yahoo.com> wrote in message
news:1177602797.417763.66620@n15g2000prd.googlegroups.com...
> Excellent ideas!! So when the power goes off, the computers will run
> from the batteries. If the batteries are depleted, and the power
> comes
> back on, will the batteries have to recharge fully before the
> computers can be used again?
>
> Thanks!
>
> On Apr 21, 7:02 pm, "Solar Flaire" <solarer...@hotmail.invalidater>
> wrote:
>
>
| |
| David Williams 2007-04-27, 5:25 pm |
| -> Excellent ideas!! So when the power goes off, the computers will run
-> from the batteries. If the batteries are depleted, and the power comes
-> back on, will the batteries have to recharge fully before the
-> computers can be used again?
No. They'll be usable as soon as the voltage at the terminals gets high
enough to supply the computers. That may well happen almost
instantaneously, when the power comes back on.
dow
| |
| PFflyer 2007-04-28, 1:25 pm |
| In order to have that kind of transfer (within a cycle or two) the inverter
needs to be synchronized to the grid before the power failure occurs. Most
simple inverters do not have this capability.
Also simple modified sinewave inverters do not have ability to ground their
common side of plug to neutral of house AC. You will need an isolation
transformer to allow this.
RC
"jevansts" <jevansts@yahoo.com> wrote in message
news:1177521575.343044.136210@n15g2000prd.googlegroups.com...
> I've set up an array of batteries with an inverter to power a few
> computers. When the AC fails, I'd like for the computers to
> automatically switch over to the battery power. Can anyone recommend a
> good and inexpensive automatic transfer switch which can accomplish
> this?
>
> I imagine the setup will look like this
>
>
> AC--------->Switch---->Computer
> ^
> Batteries->Inverter
>
> Thanks!
>
| |
| Neon John 2007-04-28, 5:25 pm |
| On Sat, 28 Apr 2007 13:04:35 -0400, "PFflyer" <ron.craig@adelphia.net>
wrote:
>In order to have that kind of transfer (within a cycle or two) the inverter
>needs to be synchronized to the grid before the power failure occurs. Most
>simple inverters do not have this capability.
Sure they do. They couldn't do bumpless transfer unless they did.
Miss even a whole cycle and a PC power supply will drop the "line
good" line and reset the computer. And if they miss that cycle then
they have to wait several more, in case there is an electric motor
attached. If there is and the motor is turning and there is any
residual excitation in the stator then it'll induction-generate out of
phase and may/probably will trip the inverter on overload.
Line sync is as simple a coupling some line voltage to the oscillator
with a simple capacitor to injection-lock the oscillator. That's the
way most every one I've looked at does it - the 60 hz oscillator runs
all the time injection-locked to the 60hz line. A missing pulse
detector gates the power stage on when the line voltage fails. The
transfer is almost seamless.
>Also simple modified sinewave inverters do not have ability to ground their
>common side of plug to neutral of house AC. You will need an isolation
>transformer to allow this.
Make that "some simple inverters". Certainly not all. Even those
that float the neutral don't matter since there is never a need to
connect the neutral and ground on an isolated system like that.
John
>
>RC
>
>"jevansts" <jevansts@yahoo.com> wrote in message
>news:1177521575.343044.136210@n15g2000prd.googlegroups.com...
>
---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
All great things are simple and many can be expressed in single words:
Freedom, Justice, Honor, Duty, Mercy, Hope. -Churchill
| |
| Solar Flaire 2007-04-29, 9:25 pm |
| Without a transformer inside to isolate the output, this means those
little gadgets run a 200 volt ni-cad battery bank inside? Not likely.
No transformer inside = no step up and the battery needs to exceed the
peak voltage of the waveform.
"Neon John" <no@never.com> wrote in message
news:2v67339lbjlpv6adrnfhjchh2875iphhfj@4ax.com...
> On Sat, 28 Apr 2007 13:04:35 -0400, "PFflyer"
> <ron.craig@adelphia.net>
> wrote:
>
>
> Sure they do. They couldn't do bumpless transfer unless they did.
> Miss even a whole cycle and a PC power supply will drop the "line
> good" line and reset the computer. And if they miss that cycle then
> they have to wait several more, in case there is an electric motor
> attached. If there is and the motor is turning and there is any
> residual excitation in the stator then it'll induction-generate out
> of
> phase and may/probably will trip the inverter on overload.
>
> Line sync is as simple a coupling some line voltage to the
> oscillator
> with a simple capacitor to injection-lock the oscillator. That's
> the
> way most every one I've looked at does it - the 60 hz oscillator
> runs
> all the time injection-locked to the 60hz line. A missing pulse
> detector gates the power stage on when the line voltage fails. The
> transfer is almost seamless.
>
>
> Make that "some simple inverters". Certainly not all. Even those
> that float the neutral don't matter since there is never a need to
> connect the neutral and ground on an isolated system like that.
>
> John
>
>
> ---
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> Cleveland, Occupied TN
> All great things are simple and many can be expressed in single
> words:
> Freedom, Justice, Honor, Duty, Mercy, Hope. -Churchill
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